The Belgian WRT team, which won the Spa enduro in 2011, will field a fourth Audi R8 LMS ultra in addition to its three regular entries in the Blancpain Endurance Series for the blue-riband round of the championship on July 27-28.

Lotterer will drive the additional entry together with Blancpain regulars Frank Stippler and Christopher Mies.Their usual teammate, Edward Sandstrom, will be joined by Fassler and Ekstrom. The lineups in the other two WRT Audis will be unchanged for Spa.

Team boss Vincent Vosse said: "This was not really expected, but we are very enthusiastic about it. We know it is a big challenge to run four cars, but we will be very well organized."

Vosse explained that WRT will be bolstered by mechanics from Audi for the event. He added that he was looking forward to running Lotterer, who counts Spa as his local circuit, in one of his cars.

"I know Andre very well; we are good friends, so I am excited that he is racing for us," he said.

Fassler and Ekstrom are former winners at Spa: Fassler won the race in 2007 with a Chevrolet Corvette C6.R run by Phoenix/Carsport Holland, while Ekstrom triumphed in 2011 with WRT.

Lotterer will be contesting the Spa 24 Hours for only the third time: he finished fifth in Freisinger Porsche 911 GT3-RS in 2002 and sixth last year in a Phoenix-run Audi R8.